If i understand your question correctly, its not whether its fake or real, but, rather whether its new or used or refurbished. I don't think you can tell. If a prior owner has done a proper factory reset and logged out of any prior wipe/lock software, then it will be pristine from a memory and software point of view. I think the only way to tell is from a physical point of view. Nearly any amount of use will result in some physical blemish or scratch somewhere. But, if someone bought it at a provider store, had it less than a day and returned it, you'll never be able to tell.